Cross-core calibration in a multi-radio system

ABSTRACT

A Radio Frequency (RF) transceiver includes a first RF transceiver group, a second RF transceiver group, local oscillation circuitry, and calibration control circuitry. Each of the RF transceiver group has an RF transmitter and an RF receiver. The local oscillation circuitry selectively produces a local oscillation to the first RF transceiver group and to the second RF transceiver group. The calibration control circuitry is operable to initiate calibration operations including transmitter self calibration operations, first loopback calibration operations, and second loopback calibration operations. During loopback calibration operations, test signals produced by an RF transceiver group are looped back to an RF receiver of another RF transceiver group.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation of and claims priority to U.S. patentapplication Ser. No. 12/569,885, filed Sep. 29, 2009. The 12/569,885application is a continuation of and claims priority to U.S. patentapplication having an application Ser. No. 11/359,222, filed Feb. 21,2006, now U.S. Pat. No. 7,616,929. The 11/359,222 application is acontinuation-in-part of and claims priority to U.S. patent applicationhaving an application Ser. No. 11/173,043, filed Jul. 1, 2005, now U.S.Pat. No. 7,356,325. The 11/359,222 application also claims priority toU.S. provisional application having an application Ser. No. 60/760,237,filed Jan. 19, 2006. The 11/173,043 application claims priority to U.S.provisional patent application having an application Ser. No.60/668,050, filed Apr. 4, 2005. All of the above-referenced applicationsare incorporated herein by reference for all purposes.

BACKGROUND OF THE INVENTION

1. Technical Field of the Invention

This invention relates generally to communication circuitry and moreparticularly to radio frequency circuits that may be used within awireless communication device.

2. Description of Related Art

Communication systems are known to support wireless and wire linedcommunications between wireless and/or wire lined communication devices.Such communication systems range from national and/or internationalcellular telephone systems to the Internet to point-to-point in-homewireless networks. Each type of communication system is constructed, andhence operates, in accordance with one or more communication standards.For instance, wireless communication systems may operate in accordancewith one or more standards including, but not limited to, IEEE 802.11(Wireless Local Area Networks “WLANs”), Bluetooth (Wireless PersonalArea Networks), advanced mobile phone services (AMPS), digital AMPS,global system for mobile communications (GSM), code division multipleaccess (CDMA), time division multiple access (TDMA), frequency divisionmultiple access (FDMA), local multi-point distribution systems (LMDS),multi-channel-multi-point distribution systems (MMDS), and/or variationsthereof.

Depending on the type of wireless communication system, a wirelesscommunication device, such as a cellular telephone, two-way radio,personal digital assistant (PDA), personal computer (PC), laptopcomputer, home entertainment equipment, et cetera communicates directlyor indirectly with other wireless communication devices. For directcommunications (also known as point-to-point communications), theparticipating wireless communication devices tune their receivers andtransmitters to the same channel or channels (e.g., one of the pluralityof radio frequency (RF) carriers of the wireless communication system)and communicate over that channel(s). For indirect wirelesscommunications, each wireless communication device communicates directlywith an associated base station (e.g., for cellular services) and/or anassociated access point (e.g., for an in-home or in-building wirelessnetwork) via an assigned channel. To complete a communication connectionbetween the wireless communication devices, the associated base stationsand/or associated access points communicate with each other directly,via a system controller, via the public switch telephone network, viathe Internet, and/or via some other wide area network.

For each wireless communication device to participate in wirelesscommunications, it includes a built-in RF transceiver (i.e., receiverand transmitter) or is coupled to an associated RF transceiver (e.g., astation for in-home and/or in-building wireless communication networks,RF modem, etc.). As is known, the transmitter includes a data modulationstage, one or more intermediate frequency stages, and a power amplifier.The data modulation stage converts raw data into baseband signals inaccordance with a particular wireless communication standard. The one ormore intermediate frequency stages mix the baseband signals with one ormore local oscillations to produce RF signals. The power amplifieramplifies the RF signals prior to transmission via an antenna.

As is also known, the receiver is coupled to the antenna and includes alow noise amplifier, one or more intermediate frequency stages, afiltering stage, and a data recovery stage. The low noise amplifierreceives inbound RF signals via the antenna and amplifies then. The oneor more intermediate frequency stages mix the amplified RF signals withone or more local oscillations to convert the amplified RF signal intobaseband signals or intermediate frequency (IF) signals. The filteringstage filters the baseband signals or the IF signals to attenuateunwanted out of band signals to produce filtered signals. The datarecovery stage recovers raw data from the filtered signals in accordancewith the particular wireless communication standard.

Currently developing operating standards require Multiple Input MultipleOutput (MIMO) operations in which multiple receivers or transmitters ofan RF transceiver operate simultaneously in a common band. RFtransceivers of this type often times support higher order modulationssuch as QPSK, 8-PSK, 16-QAM, 64-QAM, 256-QAM, 1024-QAM, etc. In order tosupport these higher order modulations, calibration of the RFtransceiver transmitters and receivers is extremely important.Therefore, a need exists for improvements in the calibration of multiplecore RF transceivers.

BRIEF SUMMARY OF THE INVENTION

The present invention is directed to apparatus and methods of operationthat are further described in the following Brief Description of theDrawings, the Detailed Description of the Invention, and the claims.Other features and advantages of the present invention will becomeapparent from the following detailed description of the invention madewith reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a schematic block diagram illustrating a wirelesscommunication system in accordance with the present invention;

FIG. 2 is a schematic block diagram illustrating a wirelesscommunication device in accordance with the present invention;

FIG. 3 is a schematic block diagram illustrating another wirelesscommunication device in accordance with the present invention;

FIG. 4 is a schematic block diagram illustrating a Radio Frequency (RF)transceiver Integrated Circuit (IC) in accordance with the presentinvention;

FIG. 5 is a schematic block diagram illustrating a portion of the RFtransceiver IC of FIG. 4 in accordance with one embodiment of thepresent invention;

FIG. 6 is a schematic block diagram illustrating a portion of the RFtransceiver IC of FIG. 4 in accordance with another embodiment of thepresent invention;

FIG. 7 is a schematic block diagram illustrating a portion of an RFtransceiver IC or multiple RF transceiver ICs in accordance with stillanother embodiment of the present invention;

FIG. 8 is a schematic block diagram illustrating a portion of an RFtransceiver IC or multiple RF transceiver ICs in accordance with yetanother embodiment of the present invention;

FIG. 9 is a schematic block diagram illustrating a portion of an RFtransceiver constructed and operating in accordance still anotherembodiment of the present invention;

FIG. 10 is a block diagram illustrating an interface between a basebandprocessing module and multiple transmitters and multiple receivers of anRF transceiver constructed and operating according to the presentinvention;

FIG. 11 is a block diagram illustrating a portion of an RF transceiverconstructed and operating according to the present invention;

FIG. 12 is a block diagram illustrating another portion of the RFtransceiver of FIG. 11 constructed and operating according to thepresent invention;

FIG. 13 is a flow chart illustrating RF transceiver calibrationoperations according to an embodiment of the present invention;

FIG. 14 is a flow chart illustrating RF transceiver calibrationoperations according to another embodiment of the present invention; and

FIGS. 15A and 15B illustrate the baseband processing module and multipletransmitters and multiple receivers of the RF transceiver of FIG. 10operating according to aspects of an embodiment of the presentinvention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 is a schematic block diagram illustrating a communication system5 that includes basic service set (BSS) areas 7 and 9, an independentbasic service set (IBSS) 11, and a network hardware device 15. Each ofthe BSS areas 7 and 9 include a base station and/or access point 17, 19and a plurality of wireless communication devices 21-23, 25-31. The IBSS11 includes a plurality of wireless communication devices 33-37. Each ofthe wireless communication devices 21-37 may be laptop host computers 21and 25, personal digital assistant hosts 23 and 29, personal computerhosts 31 and 33, and/or cellular telephone hosts 27 and 35.

The base stations or access points 17 and 19 are operably coupled to thenetwork hardware 15 via local area network connections 39 and 43. Thenetwork hardware 15, which may be a router, switch, bridge, modem,system controller, et cetera, provides a wide area network connection 41for the communication system 5. Each of the base stations or accesspoints 17, 19 has an associated antenna or antenna array to communicatewith the wireless communication devices in its area. Typically, thewireless communication devices register with a particular base stationor access point 17, 19 to receive services from the communication system5. For direct connections (i.e., point-to-point communications) withinIBSS 11, wireless communication devices 33-37 communicate directly viaan allocated channel.

Typically, base stations are used for cellular telephone systems andlike-type systems, while access points are used for in-home orin-building wireless networks. Regardless of the particular type ofcommunication system, each wireless communication device includes abuilt-in radio transceiver and/or is coupled to a radio transceiver tofacilitate direct and/or in-direct wireless communications within thecommunication system 5.

Still referring to FIG. 1, any of the wireless devices may be calibratedaccording to one or more embodiments of the present invention. Accordingto the methods and structure of the present invention, a wireless devicehas multiple transceiver groups each of which has an RF transmitter andan RF receiver. The multiple RF transceiver groups are calibrated in atleast one transmitter self calibration operation and a plurality ofloopback calibration operations. The structure and operations of thewireless devices that are calibrated according to the present inventionwill be described further with reference to FIGS. 10-15.

FIG. 2 is a schematic block diagram illustrating a wirelesscommunication device that includes a host device 18-32 and an associatedradio 60. For cellular telephone hosts, the radio 60 is a built-incomponent. For personal digital assistants hosts, laptop hosts, and/orpersonal computer hosts, the radio 60 may be built-in or an externallycoupled component.

As illustrated, the host device 18-32 includes at least a processingmodule 50, memory 52, radio interface 54, input interface 58, and outputinterface 56. The processing module 50 and memory 52 execute thecorresponding instructions that are typically done by the host device.For example, for a cellular telephone host device, the processing module50 performs the corresponding communication functions in accordance witha particular cellular telephone standard.

The radio interface 54 allows data to be received from and sent to theradio 60. For data received from the radio 60 (e.g., inbound data), theradio interface 54 provides the data to the processing module 50 forfurther processing and/or routing to the output interface 56. The outputinterface 56 provides connectivity to an output display device such as adisplay, monitor, speakers, et cetera such that the received data may bedisplayed. The radio interface 54 also provides data from the processingmodule 50 to the radio 60. The processing module 50 may receive theoutbound data from an input device such as a keyboard, keypad,microphone, et cetera via the input interface 58 or generate the dataitself. For data received via the input interface 58, the processingmodule 50 may perform a corresponding host function on the data and/orroute it to the radio 60 via the radio interface 54.

Radio 60 includes a host interface 62, digital receiver processingmodule 64, analog-to-digital converter 66, filtering/gain module 68,down conversion module 70, low noise amplifier 72, local oscillationmodule 74, memory 75, digital transmitter processing module 76,digital-to-analog converter 78, filtering/gain module 80, up-conversionmodule 82, power amplifier 84, and an antenna 86. The antenna 86 may bea single antenna that is shared by the transmit and receive paths or mayinclude separate antennas for the transmit path and receive path. Theantenna implementation will depend on the particular standard to whichthe wireless communication device is compliant.

The digital receiver processing module 64 and the digital transmitterprocessing module 76, in combination with operational instructionsstored in memory 75, execute digital receiver functions and digitaltransmitter functions, respectively. The digital receiver functionsinclude, but are not limited to, digital intermediate frequency tobaseband conversion, demodulation, constellation demapping, decoding,and/or descrambling. The digital transmitter functions include, but arenot limited to, scrambling, encoding, constellation mapping, modulation,and/or digital baseband to IF conversion. The digital receiver andtransmitter processing modules 64 and 76 may be implemented using ashared processing device, individual processing devices, or a pluralityof processing devices. Such a processing device may be a microprocessor,micro-controller, digital signal processor, microcomputer, centralprocessing unit, field programmable gate array, programmable logicdevice, state machine, logic circuitry, analog circuitry, digitalcircuitry, and/or any device that manipulates signals (analog and/ordigital) based on operational instructions. The memory 75 may be asingle memory device or a plurality of memory devices. Such a memorydevice may be a read-only memory, random access memory, volatile memory,non-volatile memory, static memory, dynamic memory, flash memory, and/orany device that stores digital information. Note that when theprocessing module 64 and/or 76 implements one or more of its functionsvia a state machine, analog circuitry, digital circuitry, and/or logiccircuitry, the memory storing the corresponding operational instructionsis embedded with the circuitry comprising the state machine, analogcircuitry, digital circuitry, and/or logic circuitry.

In operation, the radio 60 receives outbound data 94 from the hostdevice via the host interface 62. The host interface 62 routes theoutbound data 94 to the digital transmitter processing module 76, whichprocesses the outbound data 94 in accordance with a particular wirelesscommunication standard (e.g., IEEE802.11a, IEEE802.11b, IEEE 802.11g,IEEE 802.11n, IEEE 802.15, Bluetooth, et cetera) to produce digitaltransmission formatted data 96. The digital transmission formatted data96 will be a digital base-band signal or a digital low IF signal, wherethe low IF will be in the frequency range of zero to a few megahertz.

The digital-to-analog converter 78 converts the digital transmissionformatted data 96 from the digital domain to the analog domain. Thefiltering/gain module 80 filters and/or adjusts the gain of the analogsignal prior to providing it to the up-conversion module 82. Theup-conversion module 82 directly converts the analog baseband or low IFsignal into an RF signal based on a transmitter local oscillationprovided by local oscillation module 74. The power amplifier 84amplifies the RF signal to produce outbound RF signal 98. The antenna 86transmits the outbound RF signal 98 to a targeted device such as a basestation, an access point, and/or another wireless communication device.

The radio 60 also receives an inbound RF signal 88 via the antenna 86,which was transmitted by a base station, an access point, or anotherwireless communication device. The antenna 86 provides the inbound RFsignal 88 to the low noise amplifier 72, which amplifies the signal 88to produce an amplified inbound RF signal. The low noise amplifier 72provide the amplified inbound RF signal to the down conversion module70, which directly converts the amplified inbound RF signal into aninbound low IF signal (or baseband signal) based on a receiver localoscillation provided by local oscillation module 74. The down conversionmodule 70 provides the inbound low IF signal (or baseband signal) to thefiltering/gain module 68, which filters and/or adjusts the gain of thesignal before providing it to the analog to digital converter 66.

The analog-to-digital converter 66 converts the filtered inbound low IFsignal (or baseband signal) from the analog domain to the digital domainto produce digital reception formatted data 90. The digital receiverprocessing module 64 decodes, descrambles, demaps, and/or demodulatesthe digital reception formatted data 90 to recapture inbound data 92 inaccordance with the particular wireless communication standard beingimplemented by radio 60. The host interface 62 provides the recapturedinbound data 92 to the host device 18-32 via the radio interface 54.

FIG. 3 is a schematic block diagram illustrating a wirelesscommunication device that includes the host device 18-32 and anassociated radio 60. For cellular telephone hosts, the radio 60 is abuilt-in component. For personal digital assistants hosts, laptop hosts,and/or personal computer hosts, the radio 60 may be built-in or anexternally coupled component.

As illustrated, the host device 18-32 includes a processing module 50,memory 52, radio interface 54, input interface 58, and output interface56. The processing module 50 and memory 52 execute the correspondinginstructions that are typically done by the host device. For example,for a cellular telephone host device, the processing module 50 performsthe corresponding communication functions in accordance with aparticular cellular telephone standard.

The radio interface 54 allows data to be received from and sent to theradio 60. For data received from the radio 60 (e.g., inbound data), theradio interface 54 provides the data to the processing module 50 forfurther processing and/or routing to the output interface 56. The outputinterface 56 provides connectivity to an output display device such as adisplay, monitor, speakers, et cetera such that the received data may bedisplayed. The radio interface 54 also provides data from the processingmodule 50 to the radio 60. The processing module 50 may receive theoutbound data from an input device such as a keyboard, keypad,microphone, et cetera via the input interface 58 or generate the dataitself. For data received via the input interface 58, the processingmodule 50 may perform a corresponding host function on the data and/orroute it to the radio 60 via the radio interface 54.

Radio 60 includes a host interface 62, a baseband processing module 100,memory 65, a plurality of radio frequency (RF) transmitters 106-110, atransmit/receive (T/R) module 114, a plurality of antennas 81-85, aplurality of RF receivers 118-120, a channel bandwidth adjust module 87,and a local oscillation module 74. The baseband processing module 100,in combination with operational instructions stored in memory 65,executes digital receiver functions and digital transmitter functions,respectively. The digital receiver functions may include, but are notlimited to, digital intermediate frequency to baseband conversion,demodulation, constellation demapping, decoding, de-interleaving, fastFourier transform, cyclic prefix removal, space, and time decoding,and/or descrambling. The digital transmitter functions include, but arenot limited to, scrambling, encoding, interleaving, constellationmapping, modulation, inverse fast Fourier transform, cyclic prefixaddition, space and time encoding, and digital baseband to IFconversion. The baseband processing modules 100 may be implemented usingone or more processing devices. Such a processing device may be amicroprocessor, micro-controller, digital signal processor,microcomputer, central processing unit, field programmable gate array,programmable logic device, state machine, logic circuitry, analogcircuitry, digital circuitry, and/or any device that manipulates signals(analog and/or digital) based on operational instructions. The memory 65may be a single memory device or a plurality of memory devices. Such amemory device may be a read-only memory, random access memory, volatilememory, non-volatile memory, static memory, dynamic memory, flashmemory, and/or any device that stores digital information. Note thatwhen the processing module 100 implements one or more of its functionsvia a state machine, analog circuitry, digital circuitry, and/or logiccircuitry, the memory storing the corresponding operational instructionsis embedded with the circuitry comprising the state machine, analogcircuitry, digital circuitry, and/or logic circuitry.

In operation, the radio 60 receives outbound data 94 from the hostdevice via the host interface 62. The baseband processing module 64receives the outbound data 88 and, based on a mode selection signal 102,produces one or more outbound symbol streams 90. The mode selectionsignal 102 will indicate a particular mode of operation that iscompliant with one or more specific modes of the various IEEE 802.11standards. For example, the mode selection signal 102 may indicate afrequency band of 2.4 GHz, a channel bandwidth of 20 or 22 MHz and amaximum bit rate of 54 megabits-per-second. In this general category,the mode selection signal will further indicate a particular rateranging from 1 megabit-per-second to 54 megabits-per-second. Inaddition, the mode selection signal will indicate a particular type ofmodulation, which includes, but is not limited to, Barker CodeModulation, BPSK, QPSK, CCK, 16 QAM, and/or 64 QAM. The mode selectsignal 102 may also include a code rate, a number of coded bits persubcarrier (NBPSC), coded bits per OFDM symbol (NCBPS), and/or data bitsper OFDM symbol (NDBPS). The mode selection signal 102 may also indicatea particular channelization for the corresponding mode that provides achannel number and corresponding center frequency. The mode selectsignal 102 may further indicate a power spectral density mask value anda number of antennas to be initially used for a MIMO communication.

The baseband processing module 100, based on the mode selection signal102 produces one or more outbound symbol streams 104 from the outbounddata 94. For example, if the mode selection signal 102 indicates that asingle transmit antenna is being utilized for the particular mode thathas been selected, the baseband processing module 100 will produce asingle outbound symbol stream 104. Alternatively, if the mode selectsignal 102 indicates 2, 3, or 4 antennas, the baseband processing module100 will produce 2, 3, or 4 outbound symbol streams 104 from theoutbound data 94.

Depending on the number of outbound streams 104 produced by the basebandmodule 10, a corresponding number of the RF transmitters 106-110 will beenabled to convert the outbound symbol streams 104 into outbound RFsignals 112. In general, each of the RF transmitters 106-110 includes adigital filter and upsampling module, a digital to analog conversionmodule, an analog filter module, a frequency up conversion module, apower amplifier, and a radio frequency bandpass filter. The RFtransmitters 106-110 provide the outbound RF signals 112 to thetransmit/receive module 114, which provides each outbound RF signal to acorresponding antenna 81-85.

When the radio 60 is in the receive mode, the transmit/receive module114 receives one or more inbound RF signals 116 via the antennas 81-85and provides them to one or more RF receivers 118-122. The RF receiver118-122, based on settings provided by the channel bandwidth adjustmodule 87, converts the inbound RF signals 116 into a correspondingnumber of inbound symbol streams 124. The number of inbound symbolstreams 124 will correspond to the particular mode in which the data wasreceived. The baseband processing module 100 converts the inbound symbolstreams 124 into inbound data 92, which is provided to the host device18-32 via the host interface 62.

As one of average skill in the art will appreciate, the wirelesscommunication device of FIG. 3 may be implemented using one or moreintegrated circuits. For example, the host device may be implemented onone integrated circuit, the baseband processing module 100 and memory 65may be implemented on a second integrated circuit, and the remainingcomponents of the radio 60, less the antennas 81-85, may be implementedon a third integrated circuit. As an alternate example, the radio 60 maybe implemented on a single integrated circuit. As yet another example,the processing module 50 of the host device and the baseband processingmodule 100 may be a common processing device implemented on a singleintegrated circuit. Further, the memory 52 and memory 65 may beimplemented on a single integrated circuit and/or on the same integratedcircuit as the common processing modules of processing module 50 and thebaseband processing module 100.

Still referring to FIG. 3, each of the RF receivers 118, 120, and 122and RF transmitters 106, 108, and 110 may be calibrated and operateaccording to embodiments of the present invention. According to theseembodiments, the radio 60 includes a plurality of RF transceiver groups.The plurality of RF transceiver groups are calibrated using transmitterself calibration operations and a plurality of loopback calibrationoperations. These operations will be described further with reference toFIGS. 10-15.

FIG. 4 is a schematic block diagram illustrating a Radio Frequency (RF)transceiver Integrated Circuit (IC) in accordance with the presentinvention. The RF transceiver IC 300 includes a first transceiver group302, a second RF transceiver group 304, a first baseband section 352, asecond baseband section 354, local oscillation generation circuitry 307,and local oscillation distribution circuitry 306. Additional componentsof the RF transceiver IC 300 will be described subsequently herein.

The first baseband section 352 communicatively couples to the first RFtransceiver group 302. Further, the second baseband section 354communicatively couples to the second RF transceiver group 304. Thelocal oscillation generation circuitry 307 generates a local oscillationand couples the local oscillation to the local oscillation distributioncircuitry 306. The local oscillation distribution circuitry 306 operablycouples to the local oscillation generation circuitry 307, to the firstRF transceiver group 302, and to the second RF transceiver group 304.

According to a first aspect to the present invention, the second RFtransceiver group 304 resides in substantial symmetry with the first RFtransceiver group 302 about a center line of symmetry 350 of the RFtransceiver IC 300. As the reader will appreciate, the center line ofsymmetry 350 of the RF transceiver IC 300 is not formed upon the RFtransceiver IC 300 but relates to the layout of the components of the RFtransceiver IC 300. Further, the center line of symmetry 350 of the RFtransceiver IC 300 relates to the substantial but not absolutesymmetrical relationship of the components. Thus, while the first RFtransceiver group 302 and the second RF transceiver group 304 reside insubstantial symmetry with one another about the center line of symmetry350 of the RF transceiver IC 300, such symmetry may not be absolute orprecise but merely substantial. Moreover, the center line of symmetry350 of the RF transceiver IC 300 relates to the symmetrical relationshipof components of the RF transceiver IC 300 and need not reside in acentral location of the RF transceiver IC 300.

The first baseband section 352 includes a first RX baseband section 320and a first TX baseband section 324. Further, the second basebandsection 354 includes a second RX baseband section 322 and a second TXbaseband section 326. According to another aspect of the presentinvention, the second baseband section 354 resides in substantialsymmetry with the first baseband section 352 about the center line ofsymmetry 350 of the RF transceiver IC 300. As was the case with thesymmetry of the first RF transceiver group 302 with respect to thesecond RF transceiver group 304, the symmetry of the baseband section352 and 354 according to the present invention is substantial but maynot be absolute or precise. According to another aspect to thissymmetry, the first TX baseband section 324 may reside in substantialsymmetry with relation to the second TX baseband section 326 about thecenter line of symmetry 350 of the RF transceiver IC 300. Further, thefirst RX baseband section 320 and the second RX baseband section 322 mayreside in substantial symmetry with each other about the center line ofsymmetry 350 of the RF transceiver IC.

As is apparent upon review of FIG. 4, additional symmetrical and spatialrelationships exist among the functional blocks of the RF transceiver IC300. For example, the local oscillation generation circuitry 307 residessubstantially along the center line of symmetry 350 of the RFtransceiver IC 300. Such location of the local oscillation generationcircuitry 307 in conjunction with the structure of the LO distributioncircuitry 306 facilitates a uniform distribution of local oscillationsignals to the first RF transceiver group 302 and to the second RFtransceiver group 304. When the RF transceiver IC 300 supports MultipleInput Multiple Output (MIMO) communications, the timing and phasealignment of the RF signals produced by the first RF transceiver group302 and the second RF transceiver group 304 is of enhanced importance.Thus, with the structure of the LO distribution circuitry 306 about thecenter line of symmetry 350 of the RF transceiver IC 300, distributionof precisely phase aligned local oscillations is supported.

The additional components of the RF transceiver IC 300 include a PhaseLocked Loop (PLL) 312, PLL buffering circuitry 308, voltage controlledoscillator (VCO)/auto tune circuitry 310, VCO buffering circuitry 311,and crystal oscillator circuitry 314. The VCO/auto tune circuitry 310and the crystal oscillator circuitry 314 operate in conjunction with thePLL 312 to produce inputs to PLL buffering circuitry 308 and the VCObuffering circuitry. The VCO buffering circuitry 311 provides input tothe LO generation circuitry while the PLL buffering circuitry 308provides an input to the PLL 312. The structure and operation ofcircuitry for generating a local oscillation apart from the teachings ofthe present invention is generally known and will not be describedfurther herein.

The RF transceiver IC 300 further includes a digital control processor338, miscellaneous baseband/IF processing 340, miscellaneous circuitry344, miscellaneous baseband IF processing 342 and various input andoutput structures. As the reader will appreciate, the functional blockdiagram of FIG. 4 does not explicitly show connections between thevarious functional blocks of the RF transceiver IC 300. Based upon thefunction and operation of each of these functional blocks, each of thefunctional blocks will be coupled to various other of the functionalblocks to support transmittal of communication signals, control signals,power, and ground between the various functional blocks. As the readerwill appreciate, the connectivity between this various blocks isstraight forward and needs no further description herein.

The RF transceiver IC 300 includes a static digital interface 332 thatresides along an edge of the RF transceiver IC 300 that is substantiallyperpendicular to the center line of symmetry 350 of the RF transceiverIC 300. The RF transceiver IC 300 further includes a first dynamicdigital interface 334 residing along a first edge of the RF transceiverIC 300 that is substantially parallel to the center line of symmetry 350of the RF transceiver IC 300. Further, the RF transceiver IC 300includes a second dynamic digital interface 336 residing along a secondedge of the RF transceiver IC 300 that is substantially parallel to thecenter line of symmetry 350 of the RF transceiver IC 300. The digitalcontrol processor 338 communicatively couples to the static digitalinterface 332 and also resides along the center line of symmetry 350 ofthe RF transceiver IC 300 according to one aspect of the presentinvention.

The RF transceiver IC 300 includes a first baseband analog interface 316that communicatively couples to the first baseband section 352 andresides along a first edge of the RF transceiver IC 300 orientedsubstantially perpendicular to the center line of symmetry 350 of the RFtransceiver IC 300. The RF transceiver IC 300 further includes a secondbaseband analog interface 318 that communicatively couples to the secondbaseband section 354 and resides along the first edge of the RFtransceiver IC 300. Moreover, the RF transceiver IC 300 includes a firstRF analog interface 328 that communicatively couples to the first RFtransceiver group 302 and resides along a second edge of the RFtransceiver IC 300 oriented substantially perpendicular to the centerline of symmetry 350 of the RF transceiver IC 300. The second edgeresides opposite the first edge. Finally, the RF transceiver IC 300includes a second analog interface 330 that communicatively couples tothe second RF transceiver group 304 and resides along the second edge ofthe RF transceiver IC.

Still referring to FIG. 4, the RF transceiver 300 includes calibrationcontrol circuitry 345. The calibration control circuitry is operable toinitiate calibration operations of the first RF transceiver group 302and the second RF transceiver group 304. Initiation of these calibrationoperations may be in response to one or more direction(s) received fromthe baseband processing module 100. In initiating these operations, thecalibration control circuitry 345 is operable to first initiatetransmitter self calibration operations. With the transmitter selfcalibration operations, the transceivers of the first RF transceivergroup 302 and the second RF transceiver group 304 are activated totransmit RF signals. The RF signals would typically be test signals thatare measured at outputs of the RF transceiver groups 302 and 304. Withthe RF transceivers active, the calibration control circuitry 345 incombination with other components of the RF transceiver 300 and coupledbaseband processing module 100 are operable to determine transmittercalibration settings for the RF transmitters of the first RF transceivergroup 302 and the second RF transceiver group 304. Transmitter selfcalibration operations will be described further with reference to FIGS.11, 13, and 14.

Still referring to FIG. 4, the calibration control circuitry 345 is alsooperable to initiate loopback calibration operations for each RFreceiver of each of the first RF transceiver group 302 and the second RFtransceiver group 304. The calibration control circuitry 345 mayinitiate the loopback calibration operations in response to direction(s)received from the baseband processing module 100. Assuming that thefirst RF transceiver group 302 and the second RF transceiver group 304each includes a single RF transmitter and a single RF receiver, thecalibration control circuitry 345 initiates first loopback calibrationoperations and second loopback calibration operations. With the firstloopback calibration operations, calibration control circuitry 345activates the RF transmitter of the second RF transceiver group 304 andthe RF receiver of the first RF transceiver group 302. Transmissionsfrom the RF transmitter of the second RF transceiver group 304 couplewirelessly, via a parasitic path, or via a dedicated signal path to theRF receiver of the first RF transceiver group 302. Based upon thesecoupled signals, the calibration control circuitry 345 (and othercomponents of the RF transceiver) determines receiver calibrationsettings for the RF receiver of the first RF transceiver group 302.

With the second loopback calibration operations, calibration controlcircuitry 345 activates the RF transmitter of the first RF transceivergroup 302 and the RF receiver of the second RF transceiver group 304.Transmissions from the RF transmitter of the first RF transceiver group302 couple wirelessly, via a parasitic path, or via a dedicated signalpath to the RF receiver of the second RF transceiver group 304. Basedupon these coupled signals, the calibration control circuitry 345 (andother components of the RF transceiver) determines receiver calibrationsettings for the RF receiver of the second RF transceiver group 304.

According to the present invention, during the transmitter selfcalibration operations, each of the RF transmitter of the first RFtransceiver group 302 and the RF transmitter of the second RFtransceiver group 304 may be active concurrently. Because thetransmitter self calibration operations only consider signals producedby the transmitters, such concurrent pre-distortion settingdeterminations do not conflict with one another. Further, during thefirst loopback calibration operations, the RF receiver of the second RFtransceiver group 304 may also be active. Likewise, during the secondloopback calibration operations, the RF receiver of the first RFtransceiver group 302 may also be active.

FIG. 5 is a schematic block diagram illustrating a portion of the RFtransceiver IC of FIG. 4 in accordance with one embodiment of thepresent invention. With the portion of the RF transceiver FIG. 5, thefirst RF transceiver group 302 includes a first RF band transmitter 506,a first RF band receiver 502, a second RF band transmitter 508, and asecond RF band receiver 504. Likewise, the second RF transceiver group304 includes a first RF band transmitter 512, a first RF band receiver516, a second RF band transmitter 510, and a second RF band receiver514. According to the particular embodiment of FIG. 5, the second RFband is the 5 GHz band while the first RF band is the 2.4 GHz band. Asthe reader will appreciate, wireless local area network (WLAN) RFtransceivers are now called upon to operate in both the 5 GHz band andthe 2.4 GHz band. Thus, the RF transceiver IC 300 of the presentinvention supports communications in each of these bands usingrespective transmitters and receivers for each band.

As is illustrated in FIG. 5, the first RF band transmitter 506 of thefirst RF transceiver group 302 resides in substantial symmetry with thefirst RF band transmitter 512 of the second RF transceiver group 304about the center line of symmetry 350 of the RF transceiver IC 300.Further, the second RF band transmitter 508 of the first RF transceivergroup 302 resides in substantial symmetry with the second RF bandtransmitter 510 of the second RF transceiver group 304 about the centerline of symmetry 350 of the RF transceiver IC. Moreover, the first RFband receiver 502 of the first RF transceiver group 302 resides insubstantial symmetry with the first RF band receiver 516 of the secondRF transceiver group 304 about the center line of symmetry 350 of RFtransceiver IC 300. Finally, the second RF band receiver 504 of thefirst RF transceiver group 302 resides in substantial symmetry with thesecond RF band receiver 514 of the second RF transceiver group 304 aboutthe center line of symmetry 350 of the RF transceiver IC 300.

With the construct of FIG. 5, a sequential order of position of thefirst RF transceiver group 302 components from the center line ofsymmetry 350 of the RF transceiver IC 300 is the second RF bandtransmitter 508, the first RF band transmitter 506, the second RF bandreceiver 504, and the first RF band receiver 502. Further, a sequentialorder of position of the second RF transceiver group 304 components fromthe center line of symmetry 350 of the RF transceiver IC 300 is thesecond RF band transmitter 510, the first RF band transmitter 512, thesecond RF band receiver 514, and the first RF band receiver 516. Withthis construct, the transmitter/receiver pairs in a common band are notadjacent to one another. This provides spatial separation between thesecomponents to reduce coupling of TX/RX signals from a transmitter to areceiver in the common band. However, such a construct causes the localoscillation distribution to be slightly more complicated as contrastedto the structure of FIG. 6, which will be described further herein.

Further shown in FIG. 5 are the crystal oscillator 314, the VCO/autotune circuitry 310, the VCO buffering circuitry 311, the PLL 312, thePLL buffering circuitry 308, the local oscillation generation circuitry307, and the local oscillation distribution circuitry 306. According toanother aspect to the present invention, the local oscillationgeneration circuitry 307 is operable to produce a local oscillation atits output. Further, the local oscillation distribution circuitry 306operably couples to the local oscillation generation circuitry 307, tothe first RF transceiver group 302, and to the second RF transceivergroup 304. The local oscillation distribution circuitry 306 includes asplitting circuit 550 that is operable to receive the local oscillationfrom the local oscillation generation circuitry 307 and to producemultiple copies of the local oscillation. In particular, the splittingcircuit 550 includes drivers 518, 528, and 530. The input to of driver530 is the local oscillation produced by the local oscillationgeneration circuitry 307. Further, each of drivers 518 and 528 producesa copy of the local oscillation that is received by driver 530. As isshown, the splitting circuit 550 and the local oscillation generationcircuitry 307 reside substantially along the center line of symmetry 350of the RF transceiver IC 300.

The local oscillation distribution circuitry 306 further includes afirst distribution portion 552 that couples to the splitting circuit 550and that is operable to produce a first local oscillation correspondingto the first RF band based upon local oscillation, to produce a secondlocal oscillation corresponding to the second RF band based upon thelocal oscillation, and to provide both the first local oscillation andthe second local oscillation to the first RF transceiver group 302.Likewise, the second distribution portion 554 couples to the splittingcircuit 550 and is operable to produce both a first local oscillationcorresponding to the first RF band based upon local oscillation and asecond local oscillation corresponding to the second RF band based uponthe local oscillation. Further, the second distribution portion 554 isoperable to provide the first local oscillation and the second localoscillation to the second RF transceiver group 304. By locating thelocal oscillation generation circuitry 307 and the splitting circuitry550 substantially along the center line of symmetry 350 of the RFtransceiver IC 300, and by constructing the splitting circuit 550 withsubstantial symmetry about the center line of symmetry 350 of the RFtransceiver IC 300, multiple copies of the local oscillation are phasematched upon their receipt by each of the first distribution portion 552and the second distribution portion 554.

As is shown, the components of the first distribution portion 552 andthe second distribution portion 554 include drivers and divide-by-twoelements. In particular, the first distribution portion 552 includesdivide-by-two element 520 and drivers 522, 524 and 526. Further, thesecond distribution portion 554 includes divide-by-two element 531 anddrivers 532, 534, and 536. As is illustrated, the components of thefirst distribution portion 552 and the second distribution portion 554reside in substantial symmetry with one another about the center line ofsymmetry 350 of the RF transceiver IC 300. Because both the first RFtransceiver group 302 components and the second RF transceiver group 304components also reside in substantial symmetry about the center line ofsymmetry 350 of the RF transceiver IC, distribution of both the firstlocal oscillation and the second local oscillation to the variouscomponents of these RF transceiver groups 302 and 304 are time and phasealigned.

Still referring to FIG. 5, the RF transmitters 506 and 508 and RFreceivers 502 and 504 of the first RF transceiver group 302 may becalibrated according to the present invention, as will be furtherdescribed with reference to FIGS. 10-15. The RF transmitters 510 and 512and the RF receivers 514 and 516 of the second RF transceiver group 304may also be calibrated according to the present invention. The readershould appreciate, that the designation of RF transmitters and RFreceivers as being members of particular RF transceiver groups is forillustrative purposes only and does not limit the scope of the claims ofthe present invention. A minimum requirement of an RF transceiver groupis that it has at least one RF receiver and at least one RF transmitter.Thus, the RF transceiver group 302 could be characterized as having anRF transceiver group that includes RF receiver 502 and RF transmitter504 and a second RF transceiver group that includes RF receiver 506 andRF transmitter 508. Either of these RF transceiver groups may becalibrated according to the present invention.

The LO generation circuitry 307 produces an LO signal and provides theLO signal to the LO distribution circuitry 306. The LO distributioncircuitry 306 includes the LO splitting circuit 550 and distributionportions circuitry 552 and 554. The LO splitting circuitry 550 includesdrivers 518, 528, and 530. During normal operations, the RF transceiver300 transmits using both RF transceiver groups 302 and 304. Likewise,during receive operations the RF transceiver uses both RF transceivergroup 302 and RF transceiver group 304. Thus, during normal operations,all of drivers 518, 528, and 530 of LO generation splitting circuit 550are active.

With the calibration operations of the present invention, the LOgeneration circuitry 307 and the LO distribution circuitry are loadedsubstantially the same as they are loaded during transmit operations andreceive operations, i.e., of driver 518, 528, and 530 active. Thus,according to the present invention, the RF transceiver groups 302 and304 of the RF transceiver are calibrated with each of the drivers 518,528, and 530 also active. Thus, in such case, the loading on the LOgeneration circuitry 307 is substantially equal during each oftransmitter self calibration operations, first loopback calibrationoperations, second loopback calibration operations, data transmissionoperations, and data receipt operations. Further, when the RFtransceiver includes more than two RF transceiver groups, the loading onthe LO generation circuitry 307 is substantially equal during all oftransmitter self calibration operations, a plurality of loopbackcalibration operations, data transmission operations, and data receiptoperations.

FIG. 6 is a schematic block diagram illustrating a portion of the RFtransceiver IC of FIG. 4 in accordance with another embodiment of thepresent invention. With the alternate embodiment of FIG. 6, the locationof the components of the RF transceiver group 302 and the second RFtransceiver group 304 differ from the locations of correspondingcomponents of FIG. 5. FIG. 6 does not include components of the localoscillation circuitry other than the LO generation circuitry 307 and theLO distribution circuitry 306. Of course, the reader will appreciatethat the components are not shown for simplicity purposes but arerequired in the full construct of the RF transceiver IC 300.

With the embodiment of FIG. 6, a sequential order of position of thefirst RF transceiver group 302 components from the center line ofsymmetry 350 of the RF transceiver IC 300 is the second RF bandtransmitter 608, the second RF band receiver 606, the first RF bandtransmitter, and the first RF band receiver 602. Likewise, a sequentialorder of position from the center line of symmetry 350 of the RFtransceiver IC of the components of the second RF transceiver group 304is the second RF band transmitter 610, the second RF band receiver 614,the first RF band transmitter 614, and the first RF band receiver 616.As contrasted to the structure of FIG. 6, the transmitter and receiverpairs operating in a common band are adjacent one another instead ofbeing separated by an intervening component.

While the structure may result in additional coupling of a transmitsignal to its adjacent common RF band receiver, the structure allows areduced complexity of local oscillation distribution circuitry 306 to beemployed. As is shown, the local oscillation splitting circuit 650includes drivers 618, 620 and 630. The structure of the splittingcircuit 650 may be identical to that of the splitting circuit 550 ofFIG. 5. The splitting circuit 650 preferably resides along the centerline of symmetry 350 of the RF transceiver IC 300. Further, the drivers620 and 630 may be symmetrically located about the center line ofsymmetry 350 of the RF transceiver IC 300. The first distributionportion 652 includes drivers 622, divide-by-two element 624, driver 626,and driver 628. The second distribution portion 654 includes driver 632,divide-by-two element 634, driver 636, and driver 638. As contrasted tothe structure of the splitting circuit 552 of FIG. 5, the structure ofthe splitting circuit 652 of FIG. 6 is less complicated, may consumeless power, and may require less floor space for construction androuting.

Still referring to FIG. 6, the RF transceiver groups 302 and 304 may becalibrated according to the present invention. In such calibrationoperations, the loading on LO generation circuitry 307 is substantiallyequal during all of transmitter calibration operations, during receivercalibration operations, during normal transmit operations, and duringnormal receive operations of the RF transceiver.

FIG. 7 is a schematic block diagram illustrating a portion of an RFtransceiver IC or multiple RF transceiver ICs in accordance with stillanother embodiment of the present invention. In particular, FIG. 7illustrates how the structure of a first RF transceiver group 302 may beexpanded to include additional RF receivers and RF transmitters. Thestructure of FIG. 7 is similar to the structure of FIG. 5 with regard tothe orientation of RF transmitters and RF receivers in the two RF bands.In such case, the first RF transceiver group 302 includes a second RFband transmitter 702, a first RF band transmitter 704, a RF second bandreceiver 706, a first RF band receiver 708, second RF band transmitter710, a first RF band transmitter 712, a second RF band receiver 714, anda first RF band receiver 716. The components of the first RF transceivergroup 302 may be present on a single RF transceiver IC, with line 717separating a left slice (elements to the left of line 717) and a rightslice (elements to the right of line 717). Alternatively, thesecomponents may be on separate RF transceiver ICs with the separationbetween the ICs along line 717. With the structure of FIG. 7 extended toa second RF transceiver group, complimentary and correspondingtransmitter and receiver components of the second RF transceiver groupmay be included. The structure of the first RF transceiver group 302 andthe second RF transceiver group (not shown) may be substantiallysymmetric about the center line of symmetry 350 of the RF transceiver IC300.

The local oscillation distribution circuitry includes the splittingcircuits 750 and a first distribution portion 752. In such case, thesplitting circuit 750 includes drivers 718, 720, and 722. The firstdistribution portion 752 includes divide-by-two element 724 and drivers726, 728, 730, 732, 736, 738, and 740. When the first RF transceivergroup 302 resides on a single RF transceiver IC, all of the elements ofthe first distribution portion 752 reside on the single RF transceiverIC. However, if the components of the first RF transceiver group 302extend across multiple ICs, the components of the first distributionportion 752 will reside upon multiple RF transceiver ICs with separationat line 716.

Still referring to FIG. 7, the RF transceiver group 302 may becalibrated according to the present invention. In such calibrationoperations, the loading on LO generation circuitry 307 is substantiallyequal during the calibration operations and during the normal transmitand receive operations of the RF transceiver.

FIG. 8 is a schematic block diagram illustrating a portion of an RFtransceiver IC or multiple RF transceiver ICs in accordance with yetanother embodiment of the present invention. The structure of FIG. 8 mayreside on a single RF transceiver IC or upon multiple RF transceiver ICsand generally corresponds to the structure of FIG. 6. When the structureof FIG. 8 resides on a single RF transceiver IC, all of the componentsof the first RF transceiver group 302 reside upon the single RFtransceiver IC with line 817 separating a left slice from a right slice.However, when the components illustrated in FIG. 8 reside on multiple RFtransceiver ICs (e.g., along dividing line 817), some of the componentsof the first RF transceiver group 302 and distribution portion 852reside on a first RF transceiver IC while other components of the firstRF transceiver group 302 and distribution portion 852 reside on a secondRF transceiver IC.

In the construct of FIG. 8, a different ordering of the TX and RX blocksof the first RF transceiver group 302 is shown. In such case, the firstRF transceiver group 302 includes a second RF band transmitter 802, asecond RF band receiver 804, a first RF band transmitter 806, a first RFband receiver 808, a second RF band transmitter 810, a second RF bandreceiver 812, a first RF band transmitter 814, and a first RF bandreceiver 816. Also shown in FIG. 8 are local oscillation generationcircuitry 307 and local oscillation distribution circuitry 306. Thelocal oscillation distribution circuitry 306 corresponding to the firstRF transceiver group 302 includes splitting circuit 850 and firstdistribution portion 852. The splitting circuit 850 includes drivers816, 820, 852. The first distribution portion 852 includes drivers 822,826, 830, 832, 836, and 838. The first distribution portion 852 alsoincludes divide by 2 element 824. Of course, since the components shownin FIG. 8 correspond to only one-half of an RF transceiver, a seconddistribution portion (not shown) would reside substantially symmetricabout the center line of symmetry at 350 of the RF transceiver IC.

Still referring to FIG. 8, as was previously described with reference toFIGS. 5, 6 and 7, the loading on the LO generation circuitry 307 by theLO distribution circuitry 306 is substantially equal during all of thetransmitter self calibration operations, a plurality of loopbackcalibration operations, data transmission operations, and data receiptoperations.

FIG. 9 is a schematic block diagram illustrating a portion of an RFtransceiver constructed and operating in accordance still anotherembodiment of the present invention. The RF transceiver includes aplurality of components previously described with reference to FIGS. 5-8that have retained common numbering. The RF transceiver 300 includesfirst RF transceiver group 302 having an RF transmitter 904 and an RFreceiver 902. Further, the RF transceiver includes a second RFtransceiver group 304 having an RF transmitter 906 and an RF receiver908. The RF transceiver also includes local oscillation generationcircuitry 307 and local oscillation distribution circuitry 306. Thelocal oscillation generation circuitry 307 and the local oscillationdistribution circuitry 306 may be referred to together as localoscillation circuitry. The local oscillation circuitry is operable toselectively produce local oscillations to the first RF transceiver group302 and to the second RF transceiver group 304.

The LO distribution circuitry includes LO splitting circuitry 910 havingdrivers 916, 918, and 920. Further, the LO distribution circuitry 306includes first distribution circuitry 912 having driver 924 and seconddistribution circuitry 914 having driver 926. According to the presentinvention, drivers 916, 918, and 920 are active during all of selfcalibration operations, first loopback calibration operations, secondloopback calibration operations, data transmission operations, and datareceipt operations. Due to this substantially equal loading, the LOgeneration circuitry will be configured during calibration exactly as itis during data transmission and data receipt operations. Suchconfiguration allows the components of the RF transceiver groups 302 and304 to be accurately calibrated.

FIG. 10 is a block diagram illustrating an interface between a basebandprocessing module and multiple transmitters and multiple receivers of anRF transceiver constructed and operating according to the presentinvention. The RF transceiver includes RF receiver 902 and RFtransmitter 904 of a first RF transceiver group. Further, the RFtransceiver includes an RF transmitter 906 and an RF receiver 908 of asecond RF transceiver group. The RF transmitter 904 receives in-phase(TX 1 _(I)) and quadrature (TX 1 _(Q)) transmit signals from basebandprocessing module 100. Referring to both FIGS. 4 and 10, transmitsignals are not received directly from the baseband processor 100 butflow through the baseband interface 316 and the first TX basebandprocessing section 324 Likewise, the first RF receiver 902 producesin-phase (RX 1 _(I)) and quadrature (RX 1 _(Q)) signals to basebandprocessing module 100 via RX baseband processing section 320 and to thebaseband interface 316. Likewise, RF transmitter 906 receives in-phase(TX 2 _(I)) and quadrature (TX 2 _(Q)) transmit signals from basebandprocessing module 100 via the baseband interface 318 and the second TXbaseband processing section 326. Likewise, the second RF receiver 908produces in-phase (RX 2 _(I)) and quadrature (RX 2 _(Q)) signals tobaseband processing module 100 via RX baseband processing section 320and to the baseband interface 318.

Because of its operational requirements, e.g., higher order modulationrequirements, it is very important that baseband processing module 100and the RF transceiver have balanced I (in phase) and Q (quadrature)components and for all of the components to operate linearly. Thus,according to the present invention, transmitter self calibrationoperations and receiver loopback calibration operations are performedusing the receivers and transmitters of the RF transceiver. Generally,the transmitter of one RF transceiver core is used to calibrate thereceiver of another RF transceiver core during loopback calibrationoperations. As will be further described with reference to FIG. 15, boththe transmitter self calibration operations and the loopback calibrationoperations are performed while the RF transceiver is configured in anearly normal operational state. In this nearly operational state, thetransmissions of one of the RF transmitters, e.g., 904, are received byone of the RF receivers, e.g., 908, during the loopback calibrationoperations. The loopback of calibration signals may be via a wirelesspath that includes coupled antennas, via a parasitic path, or via adedicated feedback path. Performing loopback calibration operationsaccording to the present invention causes the separate I and Q phases tobe closely balanced and high linearity of the RF transceiver.

FIG. 11 is a block diagram illustrating a portion of an RF transceiverconstructed and operating according to the present invention. Thebaseband processing module 100 produces in phase TX 1 _(I) andquadrature TX 1 _(Q) analog baseband signals to the components of the RFtransmitter 904. Baseband in-phase signal TX 1 _(I) is received by inphase filtering block 1102, which filters the signal based upontransmitter calibration settings. The in phase filtering block 1102produces an output signal to in phase mixing block 1104, which mixes theinput signal with an in phase transmit local oscillation signal(LO_(TX-I)). The in phase up mixing block 1104 produces an output (RFfrequency) to driver 1106.

Q phase filtering block 1108 receives quadrature signal TX 1 _(Q) fromthe baseband processing module 100 and filters the input signal. Q phasemixing block 1110 receives the output of Q phase filtering block 1108and mixes the signal with a quadrature phase transmit local oscillationsignal LO_(TX-Q). The Q phase mixing block 1110 produces an output todriver 1112. Adder 1114 adds the outputs of driver 1106 and driver 1112to produce an RF frequency output signal. The output of adder 1114 isamplified by driver 1116, which produces an output to antenna 1118 fortransmission.

During transmitter self calibration operations, transmit path componentsare activated with a test signal by baseband processing module 100.Envelope detector 1120 then detects an envelope signal at the output ofdriver 1116. Alternatively, the envelope detector 1120 detects a signalpresent at the output of driver adder 1114. The envelope detectorproduces an output to analog signal processing block 1122 and to thebaseband processing module 100. The analog signal processing block 1122determines filter settings for the in phase filtering block 1102 and forthe Q phase filtering block 1108 for subsequent use.

Transmitter calibration setting determination operations of the basebandprocessing module 100 process the received signal to produce transmittercalibration settings for the RF transmitter of the subject RFtransceiver group. These settings may be pre-distortion settings thatare later applied by the baseband processing module 100 to a transmitbaseband signal of the subject RF transceiver group prior to producingthe baseband signal, e.g., TX 1 _(I) and TX 1 _(Q) to the RF transmitterof the subject RF transmitter group.

FIG. 12 is a block diagram illustrating another portion of the RFtransceiver of FIG. 11 constructed and operating according to thepresent invention. During its receive operations (or RX calibrationoperations), the RF transceiver receives an RF signal via antenna 1216.The RF signal is amplified by a Low Noise Amplifier (LNA) 1214 andprovided both to an in phase RX mixing block 1204 and to a Q phase RXmixing block 1210. The in phase RX mixing block 1204 mixes its inputsignal with an in phase RX local oscillation (LO_(RX-I)) to produce abaseband or low IF in phase signal, which is provided to in phase RXfiltering block 1202. The in phase RX filtering block 1202 filters itsinput signal to produce a baseband in-phase signal (RX 1 _(I))component. The quadrature phase RX mixing block 1210 mixes its inputsignal with a quadrature RX local oscillation (LO_(Rx-Q)) to produce abaseband or low IF quadrature signal, which is received by quadraturephase RX filtering block 1208. The quadrature phase RX filtering block1202 filters its input signal to produce a baseband quadrature signal(RX 1 _(Q)).

According to the present invention, during loopback calibrationoperations, receiver calibration setting determination operations of thebaseband processing module 100 determine receiver calibration settingsfor the RF receiver of the subject RF transceiver group. The basebandprocessing module 100 may apply the receiver calibration settings toperform post distortion operations on received baseband signalcomponents RX 1 _(I) and RX 1 _(Q).

FIG. 13 is a flow chart illustrating RF transceiver calibrationoperations according to an embodiment of the present invention.Operations 1300 according to a first embodiment of the present inventioncommence with enabling RF transmitters of all N RF transceiver groups(Step 1302). As was previously described, each RF transceiver group mayhave one or more RF transmitters. According to one aspect of operationat Step 1302, all RF transmitters of all N RF transceiver groups areactivated. Alternatively, some of the RF transmitters of the N RFtransceiver groups are activated while others are not activated.

Then, operation includes performing RF transmitter self calibrationoperations for the N RF transceiver groups to determine transmittercalibration settings for each of the RF transmitters of each of the Ntransceiver groups (Step 1304). Then, RF transceiver group M is selectedfor loopback calibration operations (Step 1306). The selected RFtransceiver has its RF transmitter enabled to transmit a test signalusing appropriate transmitter calibration settings that were determinedat Step 1304 (Step 1308). A received RF signal at one or more of the RFreceivers of other transceiver groups is measured (Step 1310). Operationincludes determining receiver calibration settings for the one or moreactive RF receivers based upon measured received RF signals (Step 1312).Next, a determination is made as to whether all loopback testingoperations have been completed (Step 1314). If all loopback calibrationoperations have not been completed, operation returns to Step 1306 whereanother RF transceiver group is selected for loopback calibrationoperations. Alternatively, if all of the RF transceiver group loopbackcalibrations have been completed, additional composite post-distortionsetting operations may be performed for the RF receivers of the Ntransceiver groups (optional Step 1316).

FIG. 14 is a flow chart illustrating RF transceiver calibrationoperations according to another embodiment of the present invention.Calibration operations for an RF transceiver having first and second RFtransceiver groups are illustrated in FIG. 14. Operation 1400contemplates calibration of RF transceiver groups having a single RFtransmitter and a single RF receiver. Operation 1400 commences withenabling transmitters of both the first and second RF transceiver groups(Step 1402). Operation continues with performing RF transmitter selfcalibration operations for the RF transmitters of both RF transceivergroups to determine transmitter calibration settings for each of the RFtransmitters (Step 1404). Then, operation includes enabling an RFtransmitter of the second RF transceiver group with to produce a testsignal with appropriate transmitter calibration settings (Step 1406).Operation continues with measuring the received RF signal at the RFreceiver of the first RF transceiver group (Step 1408). Operation ofSteps 1406 and 1408 includes the RF receiver of the first RF transceivergroup measuring RF signals that are transmitted by the RF transmitter ofthe second RF transceiver group. Feedback of this RF signal may occurvia a wireless feedback path, a parasitic coupling feedback path, or adedicated feedback path between the RF transmitter of the second RFtransceiver group and the RF receiver of the first RF transceiver group.Operation continues with determining receiver calibration settings forthe RF receiver of the first RF transceiver group based upon themeasured received signals (Step 1410).

Then, operation includes enabling the RF transmitter of the first RFtransceiver group to produce a test signal with appropriate transmittercalibration settings (Step 1412). Operation continues with measuring areceived signal at the RF receiver of the second RF transceiver group(Step 1414). Feedback of the RF signal produced by the RF transmitter ofthe first RF transceiver group via a wireless feedback path, a parasiticcoupling feedback path, or a dedicated feedback path between the RFtransmitter of the first RF transceiver group and the RF receiver of thesecond RF transceiver group. Finally, operation concludes withdetermining receiver calibration settings for the RF receiver of thesecond RF transceiver group based upon the measured received signals(Step 1416).

FIGS. 15A and 15B illustrate the baseband processing module and multipletransmitters and multiple receivers of the RF transceiver of FIG. 10operating according to aspects of an embodiment of the presentinvention. Referring now to FIG. 15A, the operations of FIG. 14 arefurther described. During the first loopback calibration operations, theRF transmitter 906 of the second RF transceiver group is active and thereceiver 902 of the first RF transceiver group is also active to receivea calibration signal via path 1502. Path 1502 may represent a wirelesspath that includes antennas, a parasitic coupling path, or a dedicatedsignal return path, for example. During this activation period, receivercalibration settings for the RF receiver 902 are determined. Optionally,RF receiver 908 of the second RF transceiver group may also be activatedto receive the signal transmitted by RF transmitter 906.

Referring to FIG. 15B, the configuration during second loopbackcalibration operations of FIG. 14 are described. In such case, the RFtransmitter 904 of the first RF transceiver group is active and the RFreceiver 908 of the second RF receiver group is also active to receive acalibration signal via loopback path. Path 1554 may represent a wirelesspath that includes antennas, a parasitic coupling path, or a dedicatedsignal return path, for example. During this activation period, receivercalibration settings for the RF receiver 908 are determined. In anoptional operation, RF receiver 902 of the first RF transceiver group isalso activated to receive signals from RF transmitter 904. Thus, in thisoptional embodiment, signals received during two different loopbackcalibration operations may be used to determine receiver calibrationsettings for any of the RF receivers of any of the RF transceivergroups.

As one of ordinary skill in the art will appreciate, the term“substantially” or “approximately,” as may be used herein, provides anindustry-accepted tolerance to its corresponding term and/or relativitybetween items. Such an industry-accepted tolerance ranges from less thanone percent to twenty percent and corresponds to, but is not limited to,component values, integrated circuit process variations, temperaturevariations, rise and fall times, and/or thermal noise. Such relativitybetween items ranges from a difference of a few percent to magnitudedifferences. As one of ordinary skill in the art will furtherappreciate, the term “operably coupled”, as may be used herein, includesdirect coupling and indirect coupling via another component, element,circuit, or module where, for indirect coupling, the interveningcomponent, element, circuit, or module does not modify the informationof a signal but may adjust its current level, voltage level, and/orpower level. As one of ordinary skill in the art will also appreciate,inferred coupling (i.e., where one element is coupled to another elementby inference) includes direct and indirect coupling between two elementsin the same manner as “operably coupled.” As one of ordinary skill inthe art will further appreciate, the term “compares favorably,” as maybe used herein, indicates that a comparison between two or moreelements, items, signals, etc., provides a desired relationship. Forexample, when the desired relationship is that signal 1 has a greatermagnitude than signal 2, a favorable comparison may be achieved when themagnitude of signal 1 is greater than that of signal 2 or when themagnitude of signal 2 is less than that of signal 1.

The preceding discussion has presented a phase locked loop with powerdistribution that reduces noise generated by the phase locked loop. Byreducing noise within the phase locked loop, the phase locked loop maybe used within a local oscillation generator to reduce noise therein. Asone of ordinary skill in the art will appreciate, other embodiments maybe derived from the teaching of the present invention without deviatingfrom the scope of the claims.

1. An apparatus comprising: a first transmitter; a first receiver thatoperates with the first transmitter; a second transmitter; a secondreceiver that operates with the second transmitter; and a calibrationcircuitry coupled to perform cross-calibration on the first transmitterand the second receiver and cross-calibration on the second transmitterand the first receiver by first performing transmitter self calibrationutilizing an internal feedback path, that is separate from thereceivers, to calibrate the transmitters to obtain transmittercalibration settings and, subsequently, to perform a first loopbackcross-calibration during which time the second transmitter and the firstreceiver are active to determine first receiver calibration settingsbased on feedback of second transmitter transmissions to the firstreceiver and, then, to perform a second loopback cross-calibrationduring which time the first transmitter and the second receiver areactive to determine second receiver calibration settings based onfeedback of first transmitter transmissions to the second receiver. 2.The apparatus of claim 1, wherein feedback of the first transmittertransmissions and feedback of the second transmitter transmissionsutilize wireless feedback paths.
 3. The apparatus of claim 1, whereinfeedback of the first transmitter transmissions and feedback of thesecond transmitter transmissions utilize parasitic coupling feedbackpaths.
 4. The apparatus of claim 1, wherein feedback of the firsttransmitter transmissions and feedback of the second transmittertransmissions utilize dedicated feedback paths.
 5. The apparatus ofclaim 1, wherein the transmitter calibration settings includepre-distortion calibration settings and the first and second receivercalibration settings include post-distortion calibration settings. 6.The apparatus of claim 1, further including a local oscillator coupledto the first and second transmitters and to the first and secondreceivers to provide local oscillation signals and in which, the localoscillator, the first and second transmitters, and the first and secondreceivers are integrated on a single integrated circuit chip.
 7. Theapparatus of claim 6, wherein the local oscillator includes separatedrivers to the first transmitter and receiver and to the secondtransmitter and receiver to provide substantially equal loading duringthe transmitter self calibration and during the first and secondloopback cross-calibration.
 8. The apparatus of claim 1, whereincalibrations are performed at different radio frequencies.
 9. A methodcomprising: performing transmitter self calibration on a first andsecond transmitters by utilizing an internal feedback path, that isseparate from a first receiver and a second receiver, in which the firstreceiver operates with the first transmitter and the second receiveroperates with the second transmitter during a normal mode of operation;performing, subsequently to the transmitter self calibration, a firstloopback cross-calibration during which time the second transmitter andthe first receiver are active to determine first receiver calibrationsettings based on feedback of second transmitter transmissions to thefirst receiver; and performing, subsequently to the first loopbackcross-calibration, a second loopback cross-calibration during which timethe first transmitter and the second receiver are active to determinesecond receiver calibration settings based on feedback of firsttransmitter transmissions to the second receiver.
 10. The method ofclaim 9, wherein performing the transmitter self calibration includesdetermining pre-distortion calibration settings and performing first andsecond loopback cross-calibration include determining post-distortioncalibration settings for the first and second receivers.
 11. The methodof claim 9, further comprising providing local oscillation signals froma local oscillator coupled to the first and second transmitters and tothe first and second receivers.
 12. The method of claim 11, whereinperforming the self calibration and the first and second loopbackcross-calibrations are performed on the first and second transmitters,the first and second receivers and the local oscillator that areintegrated on a single integrated circuit chip.
 13. The method of claim12, wherein providing the local oscillation signals from the localoscillator includes using separate drivers to the first transmitter andreceiver and to the second transmitter and receiver.
 14. The method ofclaim 13, wherein providing the local oscillation signals by using theseparate drivers of the local oscillator includes using the separatedrivers to provide substantially equal loading during the transmitterself calibration and during the first and second loopbackcross-calibrations.
 15. The method of claim 9, wherein performing thecalibrations are performed at different radio frequencies.
 16. Themethod of claim 9, wherein performing first and second loopbackcross-calibrations, feedback of the first transmitter transmissions andfeedback of the second transmitter transmissions utilize wirelessfeedback paths.
 17. The method of claim 9, wherein performing first andsecond loopback cross-calibrations, feedback of the first transmittertransmissions and feedback of the second transmitter transmissionsutilize parasitic coupling feedback paths.
 18. The method of claim 9,wherein performing first and second loopback cross-calibrations,feedback of the first transmitter transmissions and feedback of thesecond transmitter transmissions utilize dedicated feedback paths.